Now that's a 'loaded' question. There's probably several things one can do. Recrown if it's nicked,get a scope,try different types of ammo and practice,practice,practice. I guess it could depend on what kind of .22,rifle pistol? How much do you want to invest$
A 22 cal is a very picky creature 9 times out of 10 your problem with 22 accuracy is what you are feeding it, as with any fire arm, you have to find out what kind of ammo it likes to eat, you can take two of the same guns right off the perduction line and they will shoot diferantly, I have found that CCI workes best I all my guns as a go to round, but each gun will shoot differant brands of ammo with differant results in accuracy, another thing that comes into play is bullet weight just to confuse you a little more, So what I would suggest is clean your guns bore. go to the store and buy differant brands of ammo Remington,winchester,CCI,Federal, buy two small 50 round packs one in 32 grain and one in 40 grain of each brand, now when you sight in your gun and your printing on paper, do not mess with sights at all, pick one place to aim on your target and shoot four 3 shot groups, it dose not matter where you are hitting what we are looking for is a paturn and with each brand shoot one target with each bullet weight, it is inportant that you dont move or try to ajust your sights during this exersize, when you are done you should have two targets, in two bullet weights, for each brand of ammo you used, compare the heavy bullets with each other and the same for the lighter bullets, pick the target with the best smallest group in each weight class and that is the ammo your gun prefers, now take the ammo that printed the best in the heaver bullet and fine tune your rifle to that ammo.
I would sight in at 25 yards, You can do as you see fit you get the general Idea. Hope this helps.